Hello. My MPPT 75/15 is not increasing the voltage during Bulk. It stays below 13.6 for 6-8 hours. Then it goes up to 14+ for a few minutes. I have two Expion 360, 100 ah batteries and 200 watts of solar. I have the battery settings per the Expion recommendations. SmartShunt is saying the batteries get fully charged every day. Please help. Thanks!!